Piper's Pit BBS/FTP: ibm 0000 - 0009/ibm0000-0009/ibm0003.tar/ibm0003/LCNOW2.ZIP/EXAMPLES/LCGDEMO.C

C/C++ Source or Header | 1988-08-03 | 5.0 KB | 202 lines

/*
 * L C G D E M O
 *
 * This is a Learn C graphics demonstration program.  Its purpose
 * is to show how to select a graphics mode, draw some shapes and
 * text, and then return to DOS after restoring the user's
 * previous video environment.
 */

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <graph.h>
#include <math.h>

#define A_BRIGHTYELLOW  14
#define K_ESC           27
#define MSG_ROW         25
#define MSG_COL         2
#define MSG_WIDTH       38
#define M_NOWAIT        0
#define M_WAIT          1
#define MODE_ERR        0
#define NCOLORS         16
#define R_HORIZ         -140
#define R_VERT          0
#define R_HEIGHT        80
#define R_WIDTH         150
#define R_BORDER        0
#define R_FILL          1

/*
 * Color table -- convert color index to universal color number.
 */
Long colortab[] = {
    _BLACK, _BLUE, _GREEN, _CYAN
    _RED, _MAGENTA, _BROWN, _WHITE
    _GRAY, _LIGHTBLUE, _LIGHTGREEN, _LIGHTCYAN
    _LIGHTRED, _LIGHTMAGENTA, _LIGHTYELLOW, _BRIGHTWHITE
};

/*
 * Function prototypes
 */
void Message(short, short, char *, short);
void Rectangle(short, short, short, short, short);

int
main(void)
{
    struct videoconfig config;  /* video configuration data */
    short x_org, y_org;         /* coordinates of the origin */
    short x_ul, y_ul;           /* upper left corner */
    short x_lr, y_lr;           /* lower right corner */
    short x, y;                 /* current coordinates */
    short x_offset, y_offset;   /* offsets */
    short color;                /* color number */
    short divisor;              /* to keep color number in range */
    short delta;                /* columnar offset */

    /*
     * Set up the medium-resloution graphics,
     * set the logical origin to center of screen,
     * and set up a text window.
     */
    divisor = 16;
    if (_setvideomode(_MRES16COLOR) == MODE_ERR) {
        divisor = 4;
        if (_setvideomode(_MRES4COLOR) == MODE_ERR) {
            fprintf(stderr, "Can't set graphics mode\n");
            exit (1);
        }
    }
    _getvideoconfig(&config);
    x_org = config.numxpixels / 2 - 1;
    y_org = config.numypixels / 2 - 1;
    _setlogorg(x_org, y_org);
    _settextwindow(MSG_ROW, MSG_COL, MSG_ROW,
               MSG_COL + MSG_WIDTH - 1);
    _settextposition(MSG_ROW, MSG_COL);
    _settextcolor(A_BRIGHTYELLOW);

    /*
     * Draw a stack of rectangles in different colors.
     */
    x = R_HORIZ;
    y = R_VERT;
    x_offset = 0;
    y_offset = 0;
    for (color = 0; color < NCOLORS; ++color) {
        _setcolor(color % divisor);
        Rectangle(R_FILL, y + y_offset, x + x_offset,
              y + R_HEIGHT + y_offset, x + R_WIDTH +
              x_offset);
        _setcolor((NCOLORS - 1 - color) % divisor);
        Rectangle(R_BORDER, y + y_offset, x + x_offset,
              y + R_HEIGHT + y_offset,
              x + R_WIDTH + x_offset);
        x_offset += 8;
        y_offset -= 6;
    }

    /*
     * Create a text window and slide the "quit" message into
     * view from right to left and then wait for a keypress.
     */
    _wrapon(_GWRAPOFF);
    for (delta = MSG_WIDTH; delta >= 0; --delta)
        Message(MSG_ROW, MSG_COL + delta,
            "Press a key to quit.", M_NOWAIT);
    Message(MSG_ROW, MSG_COL + delta,
    "Press a key to quit.", M_WAIT);

    /*
     * Restore the original video mode and
     * return control to the operating system.
     */
    _setvideomode(_DEFAULTMODE);

    return (0);
}


/*
 * Rectangle()
 *
 * Draw a rectangle in the current color.  The type
 * parameter controls whether the rectangle is drawn
 * as a border only or as a filled (solid) object.
 */

void
Rectangle(short type, short top, short left, short bottom,
      short right)
{
    short x, y;

    switch (type) {
    case R_BORDER:
        /*
         * Construct a box from four line segments.
         */
        _moveto(left, top);
        _lineto(right, top);
        _lineto(right, bottom);
        _lineto(left, bottom);
        _lineto(left, top);
        break;
    case R_FILL:
        /*
         * Make a solid box from a series of
         * adjacent horizontal lines.
         */
        for (y = top; y <= bottom; ++y) {
            _moveto(left, y);
            _lineto(right, y);
        }
        break;
    default:
        break;
    }
}


/*
 * Message()
 *
 * Display the message text at the specified screen
 * location (row, col).  If wait has a non-zero value,
 * wait for the user to press a key.  When the user complies,
 * grab the character from the keyboard buffer so it won't
 * interfere with the calling program following the return.
 */

void
Message(row, col, text, wait)
short row, col; /* text position */
char *text;     /* text pointer */
short wait;     /* wait flag */
        /* (wait != 0 means wait for a keypress) */
{
    int k;      /* key code */

    /*
     * Write the prompt text at the specified location.
     */
    _settextposition(row, col);
    _outtext(text);

    /*
     * If the wait flag is set, wait for a key to be pressed,
     * then remove the code from the keyboard buffer.  Handle
     * extended codes by grabbing two bytes if the first is NUL.
     */
    if (wait) {
        k = getch();            /* read the character */
        if (k == '\0')
            /* extended code -- get the scan code */
            getch();
    }
}